MAPREDUCE-3685. Fix bugs in MergeManager to ensure compression codec is appropriately used and that on-disk segments are correctly sorted on file-size. Contributed by Anty Rao and Ravi Prakash.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1453365 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4544. Error in deleting blocks should not do check disk, for all types of errors. Contributed by Arpit Agarwal.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1453436 13f79535-47bb-0310-9956-ffa450edef68
Merging trunk to branch-trunk-win

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-trunk-win@1453456 13f79535-47bb-0310-9956-ffa450edef68